A "disturbance" is something that interrupts the normal status of things. It is the result of the action of "disturbing." Thus, a disturbance could be a loud sound in a quiet neighborhood but also could be a riot that causes a city to shut down because of the violence. Indeed, even agitated emotions can be a disturbance, as when someone gets very angry about things and then cannot think clearly.

The word "porous" comes from the same roots as the word "pore"—yes, meaning the things on your skin! You can think of pores as kinds of holes in the surface of the skin. Therefore, the general meaning of "porous" is full of small holes that let things pass through. Thus, a porous surface can be called "permeable," which also describes something that is not locked up but, instead, lets certain materials through. A "permeable membrane" is a kind of membrane that allows water and other substances through it.

The general idea of something being "absolute" is of something that is unmoving and unchanging. This is opposed to being "relative." We speak of "'relative" matters when we say things like, "The desk is tall, at least in comparison to the pea on the ground," and "George is more handsome than Harold." However, the word "absolute" can then be extended to mean "unlimited." Whenever something is "unlimited," there is nothing relative to it that can limit its exercise or force. Thus, "absolute power" is unlimited power that has no check on it whatsoever.

The word "perceptive" clearly is related to "perception" or "to perceive." When we perceive something, we either sense it or understand it. For example, you might say, "He perceived the danger of the situation," meaning that the person understood that the situation was dangerous. A "perceptive" person is someone who has the ability to understand. Hence, he or she could well be called "insightful," indicating his or her clear "vision"—meaning that he or she has a clear ability to understand things. Likewise, we can describe something like remarks as being "perceptive," meaning that they express matters intelligently.

Whenever something is "habitual," it has become a fixed and regular habit. For example, someone might habitually tap his foot, meaning that he regularly taps it no matter where he is at. Likewise, a person who regularly smokes cigarettes is rightly called a "habitual smoker." The word can be used to describe any settled way of acting; hence, the word "customary" is a good option for this question. "Customs" are the kinds of things that we establish in our culture and just "keep doing" without thinking too much. Hence, there are customs like saying "thank you," but also customs like buying flowers for those whom we love. We do these things out of a kind of habit. Hence, the word "customary" is a good option among those provided here.